Tunable electronic properties, migration mechanism and quantum capacitance of Zr2CO2 monolayer by electric filed effects

Abstract

MXenes have received a lot of attention because of the excellent structure and outstanding properties. Electric field-induced changes in electronic properties and quantum capacitance of Zr2CO2 monolayer are explored theoretically. The negative cohesive energy confirms the stability of Zr2CO2 monolayer under external electric field (EEF). Zr2CO2 undergoes the indirect-direct transition at 0.4 V/Å, and the semiconductor-metal transition at 0.5 V/Å. Band gap is not sensitive to the smaller EEF, but sensitive to larger EEF. All systems are all potential cathode materials in ionic/organic system. Zr2CO2 under 0.5 V/Å is a potential anode electrode in aqueous system. The quantum capacitances of Zr2CO2 under EEF in whole voltage at 233 K and 353 K are further explored. The widen voltage changes Zr2CO0.78F1.11(OH)0.11 from anode material in aqueous system to cathode material in ionic/organic system. The spatial charge distribution of Zr2CO2 MXene is also analyzed.